Advanced Propulsion

Module aims

This is an advanced course in the aerodynamic and thermodynamic analysis of propulsion systems for high-speed flight. The fundamental physics of compressible, reacting flows will be reviewed. The design and analysis of supersonic intakes and both external and internal compressors will be introduced. The limitations of subsonic combustion will be discussed, in the context of high-speed flight. You will also be introduced to design practice for diverging nozzles; propulsion systems for high-altitude, high speed flight, including solid, liquid and hybrid rocket engines, pulse-jets and pulse-detonation engines, including the thermodynamic cycle analysis of these systems.

Learning outcomes

On successfully completing this module, you should be able to: 1. Identify and carry out a thermodynamic and gas dynamic analysis of engines used in high-speed flight; 2. Identify and explain the limitations of conventional turbofans and turbojets in high-speed applications;  3. Explain the limitations of ramjets and the complexities of supersonic ramjets;  4. Analyse a number of non-air-breathing and combined-cycle engines;  5. Analyse the thermodynamics of combustion and detonation;  6. Design inlet geometries to extend the operational envelope of turbojets to supersonic flight; 7. Design compressor nozzles geometries for high-speed applications; 8. Design and carry out a thermodynamic and gas dynamic analysis of a complete ramjet engine. AHEP Learning Outcomes: SM7M, SM8M, EA6M, EA5m, EA7M 

Module syllabus

Overview of history and challenges of high-speed flight; review of compressible flow (governing equations, isentropic flow, normal shocks, oblique shocks and P-M waves).   Limitations of conventional turbomachines in high-speed flight; extension of turbojet envelope, design of supersonic inlets and techniques for shock-swallowing; external compression and ramp inlet design.    Ramjets. Intake-to-nozzle design of ramjet engines for specified flight conditions, including thermodynamic efficiency and cycle analysis.    Supersonic nozzle design. Review of method of characteristics for 2-D nozzles, and Rao's method for length-thrust trade-off. External expansion, exact and approximate spike nozzle design.  Rocket engines. Concepts of monoand bi-propellant propulsion. Review of rocket types: cold-gas, hot-gas, gas-pressurized, solid fuel, turbopump and hybrid. Dynamics of singleand multi-stage rocket launch; analytical justification of staging. Thermodynamic cycle analysis of turbopumps with cryogenic fuels; Rankine cycle with liquid hydrogen; practical design issues for cryogenic turbopumps.    Hybrid propulsion systems. Analytical justification for airborne rocket launch. Rockoons, air-launched rockets and the HARP Martlet. Turbomachine boosting and oxidizer-injection; thermodynamic analysis of mass-injection pre-compression cooling, experimental findings and coolant issues. Compressionless propulsion, harmonic pulse-jets and the Lenoir cycle.    Pulse-detonation engines. Introduction to detonation thermodynamics and the Chapman-Jouguet model. Thermodynamics and gas-dynamics of detonations and the thermodynamic efficiency of the Humphrey cycle. Approximate methods for the determination of detonation velocity in hydrogen-air mixtures; introduction to fuel-air detonation data plots and approximate methods for pulse-detonation engine design. Practical issues in PDE design, material limitations and the continuous-detonation engine.  Alternative energy in aviation. The concepts of energy-density and power-density. Comparison of hydrogen-air, hydrogen-oxygen and hydrocarbon-air combustion to existing alternative energy sources. Batteries, fuel cells and bio-kerosene. Combustionless turbopropulsion. HALE aircraft propulsion, dirigibles and safety considerations. 

Pre-requisites

Teaching methods

The module will be delivered primarily through large-class lectures introducing the key concepts and methods, supported by a variety of delivery methods combining the traditional and the technological.  The content is presented via a combination of slides, whiteboard and visualizer.Learning will be reinforced through tutorial question sheets and laboratory exercises, featuring analytical, computational and experimental tasks representative of those carried out by practising engineers.The module will also include individual and group project work, in which you can benefit from team-based learning.

Assessments

This module presents opportunities for both formative and summative assessment.  

You will be formatively assessed through progress tests and tutorial sessions. 

You will have additional opportunities to self-assess your learning via tutorial problem sheets. 

You will be summatively assessed by a written closed-book examination at the end of the module as well as through a piece of coursework. 

Assessment type Assessment description Weighting Pass mark
Examination Closed-book written examination 75% 50%
Coursework Coursework 25% 50%

You will receive feedback following the coursework submission.
You will receive feedback on examinations in the form of an examination feedback report on the performance of the entire cohort.
You will receive feedback on your performance whilst undertaking tutorial exercises, during which you will also receive instruction on the correct solution to tutorial problems.
Further individual feedback will be available to you on request via this module’s online feedback forum, through staff office hours and discussions with tutors. 

Reading list

Module leaders

Dr David Birch